12AX7
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Curious copper reaction
Crystallizing the soupy, deep green solution left from oxidizing copper with chlorate, I got a crop of moist, green crystals of variable shape. (On closer inspection, I appear to have a mixture of
CuCl2 needles and somewhat lighter colored tabular crystals -- Na2CuCl4 perhaps?) I placed these to dry on several layers of paper towel, lightly
weighted between two sheets of cardboard to encourage contact with the paper, soaking out a maximum of liquid to minimize caking. I left that for a
night, then put it in the cabinet to dry.
After some time drying, I opened the sheets, finding crusty, not-quite-dry material. But I found brownish spots all over! Especially around the
edges, and especially around the surface of the material, but these spots can be found throughout.
What from? On closer inspection, the spots look crystalline (either pseudomorphs after the granular material, or new crystals in themselves), and
have a bronze or copper color! Wild!
Did I make copper crystals? How? I know copper and cellulose do not get along favorably to say the least, but I've never had a problem over just a
few days, and I've never seen reduction like this! The solution wasn't especially acidic. This paper was reused, which might have something to do
with it, but it wasn't used very harshly (which is why I reused it). Maybe the key was the exclusion of air by compression? But then why was there
more around the perhiphery? The most remarkable part of this is the sheer size of the crystals: the only other time I've seen copper crystals was
resulting from electrolysis of an acidic copper chloride solution (with some thiourea), which created dendritic, angular deposits.
I suppose the next step is to perform an independent experiment in this manner. I could take the remains of the above paper towels, pack them with
CuCl2 (of known quality) and some moisture inside a sealed jar, and see if there is any reaction over time. I could also run a seperate test with
other types of paper to see if there might be something special about the quality of paper I used here.
Tim
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YT2095
International Hazard
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Registered: 31-5-2003
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nice Chocolate mint icecream 
is it possible the granules are Cu2O?
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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12AX7
Post Harlot
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That may be -- I tested one today and it's quite brittle, smashing to brown powder under the tap of a hammer. Cu(I) would be much easier to reduce to
than Cu(0).
The shape of that particular crystal was tabular, rectangular, with angled ends. If that rings any cuprite bells, then that could be it.
Tim
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YT2095
International Hazard
Posts: 1091
Registered: 31-5-2003
Location: Just left of Europe and down a bit.
Member Is Offline
Mood: within Nominal Parameters
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Cu2O is listed as Cubic in my data book.
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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